[GitHub] [cassandra] krummas commented on a change in pull request #1290: [CASSANDRA-14898] Fix performance issue of keycache not loading fast.

[GitBox <gi...@apache.org>]

krummas commented on a change in pull request #1290:
URL: https://github.com/apache/cassandra/pull/1290#discussion_r763002911



##########
File path: src/java/org/apache/cassandra/service/CacheService.java
##########
@@ -472,7 +482,23 @@ public void serialize(KeyCacheKey key, DataOutputPlus out, ColumnFamilyStore cfs
             int generation = input.readInt();
             input.readBoolean(); // backwards compatibility for "promoted indexes" boolean
             SSTableReader reader = null;
-            if (cfs == null || !cfs.isKeyCacheEnabled() || (reader = findDesc(generation, cfs.getSSTables(SSTableSet.CANONICAL))) == null)
+            if (!skipEntry)
+            {
+                Pair<String, String> qualifiedName = Pair.create(cfs.metadata.ksName, cfs.metadata.cfName);
+                Map<Integer, SSTableReader> generationToSSTableReader = cachedSSTableReaders.get(qualifiedName);
+                if (generationToSSTableReader == null)
+                {
+                    generationToSSTableReader = cfs.collect(SSTableSet.CANONICAL,

Review comment:
       could we just build the map here? Don't see a need for the new collect(...) method beyond this
   
   if we want to keep the method there should probably be tests for it as well

##########
File path: conf/cassandra.yaml
##########
@@ -286,7 +286,11 @@ counter_cache_save_period: 7200
 # If not set, the default directory is $CASSANDRA_HOME/data/saved_caches.
 # saved_caches_directory: /var/lib/cassandra/saved_caches
 
-# commitlog_sync may be either "periodic" or "batch." 
+# Max amount of time in seconds server has wait for cache to load while starting the Cassandra process.
+# Cache will not load (during startup) if this value is negative as there is no time left to load.
+# max_cache_load_time: 30

Review comment:
       maybe name this `max_cache_load_time_seconds` to make it clearer




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